Method of and apparatus for producing fire extinguishing foam



API 10, 1934; G. G. URQUHART 1,954,154A

uni-Hon op .AND-APPARATUS FOR PnoDUcING FIRE EXTINGUIsHlNG FOAM Filed April 8, 192,9 2 sheets-sheet' 1 j qv 3jaar April 1o, 1934.

4 G. G. URQUHART METHOD OF AND" APPARATUS FOR PRODUCING FIRE EXTINGUISHING FOAM 2 Sheets-.Sheet /W/ Mi W M W eorye J Patented Apr, '10, 1934 PATENT oFFicE vMETHOD .0F AND APPARATUS FOR PRO- DUCING FIRE EXTINGUISHING FOAM i George Gordon-Urquhart, Cynwyd, Pa.

Application April 8, 1929,'Seral No. 353,510' 6 claims. (c1. 169-15) My invention is designed to provide an improved method of and apparatus for forming foam by supplying suitable reactive chemicals to t a flowing stream, The chemicals most commonly used are bicarbonate of soda and aluminum sulphate, which react to form gas, and a stabilizer, such `as liquorice extract, legume extract, casein, saponin, or the like which forms a tenacious film on the bubbles formed by the gas so that the fire 10 may be smothered by a blanket of foam comprising bubbles containing non-combustible gas. SuchJ chemicals must be stored separately in y `tanks of large capacity if kept in liquid form and tend to' seriously deteriorate in storage when ,15 mixed-together in powdered form. Such powdered mixtures also tend to clog, arch over and permit the leakage of air when it is sought to draw them into a. flowing stream by suction-induced by the flow of such stream through an 0 ejector. Moreover should such mixed `chemicals become damp or wet in storage or while in the hopper from which powder flows to the ejector nozzle, foam is immediately formed and lost r since foam formed in the hopper cannot be ef- 2" fectively and economically drawn through the ejector into the flowing stream. Preferably, therefore, the reactive chemicals are stored and fed separately to the flowing stream; the stabilizer in powdered form preferably being mixed with the bicarbonate o f soda. This does not, however, overcome the bridging over of the chemicals when ground to a fine powder or the infiltration of air and breaking of the vacuum when coarsely ground chemicals are used. Consequently the feed of the separate chemicals varies irregularly and poor foam may result due to improper proportions of the chemicalsJbeing fied to the flowing stream in dry form. l

My improvements overcome all of the foregoing difficulties and furthermore permit the formation of foam of any desired 'cl'aracten ranging from the thin, readily flowing foam commonly used for extinguishing some inflammable liquids, such as petroleum, to the thick, dense, viscous foam which is desirable for extinguishing volatile liquids, high boiling point asphalts, as well as burning surfaces. a V

In the preferred practice of my invention, the reacting chemicals are separately fed to the iiowing stream and preferably by suction created thereby after one or both of them has had sufficient liquid added thereto to form a saturated solution or, partially dissolved slurry. The liquid 4is preferably introduced in the form of an agitating jet supplied from the main stream and the solution or slurry formed effectually prevents any infiltration of air and is readily drawn into the 4main stream by the suction resulting from the passage of the latter through an ejector. By varying the quantity of liquid admitted into the 60v chemical-containingreceptacles the rates of feed of the separate chemicals into the main stream can be widely Varied without any substantial variation in the pressure or volume of the main stream.

Ordinarily greater difficulty is experienced in feeding the aluminum sulphate than in feeding the mixed bicarbonate of soda and stabilizer, and under certain conditions it may be found desirable to supply liquid to only one of the chemicals prior to the introduction thereof into the main stream, but ordinarily it is preferable to supply liquid to both chemicals, through the amounts supplied to the `several chemicals may differ.

Preferably the wetted chemicals, which are separately non-foaming or inert, are supplied to theA flowing stream at substantially the same locus through a partitioned hopper having sepal' rated ,chambers`Y communicating with the chamber or inlet of an ejector', but the chemicals may S0 be supplied to separate' receptacles connected with separate ejectors connected with the `flow- 4ing stream in parallel, and the sealing solvent fed to the chemicals may be supplied by bypassing portions of the main stream through the supply receptacles.

The characteristic features and advantages ofmy improvements will more fully appear from the following description and the accompanying drawings illustrating an embodiment of apparatus for. the practice of my method.v a

In the drawings, Fig. 1 is a perspective View of a foam generator embodying a preferred form of my improved apparatus; Fig. 2 is a side elevation thereof; Fig. 3 is a longitudinal sectional 95 View thereof; Fig. 4 is an end view of the generator, with the funnel broken away; Fig. 5 is an. end view of the generator with a modified control for v'the by-passed sealing solvent; Fig. 6 is a top plan view of the modified construction shown in Fig.`5; Fig. 7 is a vertical sectional view of a valve mechanism of aA form suitable for use in the deviceillstrated in Figs. 5 and 6; and Fig. 8 is a horizontal sectional view of such valvev mechanism.

As illustrated in the drawings, a body 1v has formed therein a tapering passage or bore 2 and a 'cylindrical passage or bore 3. A cylindrical tube 4 is inserted in the bore '3 with its tapered nose 5 adjacent to the smaller end of the passage 110 2 and may be held in position by a ring coupling 6 engaging a rib on the tube 4 and-threadedon the body 1. "The tube 4 contains an axial passage 7 tapering to the cylindrical throat 8 and forming with the passage 2 an ejector of the Venturi tube type. 'I'he recess between the nose 5 and the end wall of the passage 2 communicates, through a port 9, with a supply chamber/or hopper 10 formed partly in the boss 11 on the body 1 and partly by a pyramidal funnel 12 connected to the body by a. ring coupling 13 engagng the funnel and threaded on the body.

The hopper is divided into two chambers 14 and 15 by a sectional partition 16 having its upper portion xed to the funnel 12 and its lower portion flxed in the boss 11, so that substancesr` supplied separately on opposite sides of the partition are maintained separate until drawn into the mouth of the ejector.

The tube 4 has a peripheral channel 17 formed therein communicating through ports 18 with the passage 7. Passages 19 and 20 formed in the boss 11 communicate with the channel 17 and witli the respective chambers 14 and 15 to which they discharge through similar ports-21V so disposed as to eiect desired agitation of the contentsof the chambers and form a freely moving suspension or slurry. The passage of iiuid through the passages 19 and20 is controlled by the respective having therein the diverging passages 28 and 29;

the former 'connecting -the passage 7 with the chamber ofthe quick opening inlet valve' 30, and the latter containing the cylindrical screen 31 through which the 'water admitted to the generator passes. The screen may be`flushed for the removal of accumulated detritus, even during the operation of the generator, by opening the valve or plug controlled port 32 to which may be atmy improved apparatus water under pressure passes through the inlet'valve 30, screen 31, Venturi tube formed by the passages 7 and 2 and lifts the clapper valve 33. 'Ihe flow through the Venturi tube vcreates a suction at the throat 8 which draws into such throat separately inert chemicals supplied to the chambers 14 and 15. Ingltration of air through such chemicals isprevented, the rate of feed oi' the chemicals relative to one another and to the stream is controlled and the solution and reaction of the chemicals in the passage 2 is expedited by the introduction into the respective chambers 14 and 15 of regulated amounts of water, by-passed through the mechanism described. The use of a single valve, as illustrated in Figs. 5 and 6, or by coupling the valve stems as illustrated in Fig. 4, a predetermined total quantity of Water may be fed to the chemicals before introduction into the main stream to produce foam of desired consistency, and the variation of the relative amounts of water introduced into the respective compartments 14 lintroduction thereof into the flowing stream and tached a small hose for supplyingwater to or washing out the hopper.

The forward end of the body 1 has xed thereto a body section 1" containing the nonreturri clapper valve 33.

Thebody sections `1, 1' and 1" may be*` pro- .videdwith supporting brackets or feet 34, 35 Vand 36, and the sections 1 and 1" may be provided with Handles 37 and 38.

is illustrated in Figs. 5 and 6, the flow of sealingifluid to the respective chambers 14 and 15 may be controlled by a single valve 40 positioned at-the juncture between the passage 41 communicating with the channel 17 and the passages "42 and 43 communicating with the respective `chambers 14 and 15. The ports in the valve and f valve seat are so positioned that the movement of the valve 40 in one direction increases the flow of sealing fluid tothe chamber 14 and increases the flow to the chamber 15; whereas movement of the valve in the opposite direction increases the flow to the chamber'l and decreases the flow to the chamber 14' thereby varying the relative amount of foam 'forming chemicals introduced into the flowing stream by varying the amount of water mixed with the respective chemicals before the introduction thereof into such stream.

It will be understood that'in the operation 0f the consistency of the foam thereby varied.

When the clogging of the ,screens 31 is indicated Aby a drop in the pressure shown on the gage 45, the valve or plug 32 may be opened and the screen flushed without interrupting the operation of the generator, and by connecting a hose with the passage 29 and discharging therefrom into the chambers 14 and. 15 the flow of water through @the by-passes described may be supplemented or superseded.

By my improvement, it is possible to utilize freely flowing foam forming chemicals and thereby avoid the piping occurring=in chemicals in a hopper when the chemicals used are of suicient iineness to be drawn into the ejector in foam forming quantities. Where chemicals are used of such flneness that the suction thereof into the ejector causes piping through the chemical mass in the hopper,` the chemicals are drawn into the stream irregularly and foam is formed in disconnected bodies emitted from theLnozzle in pulsating jets instead of in a continuous stream of uniform consistency such as results from the practice of my` invention. The chemicals which may be used in the practice of my improvement are preferably of sufiicient coarseness or porosity to permit the passage through a 20 column thereof of sufficient air to neutralize a vacuum drawing 10" of mercury and toliave an angle of repose ofA less than 70.` By my improvements there may beformed, as required for use, separate concentrated aqueous dispersions of separately inert reacting chemicals, which are fed simultaneously separately in to a stream or streams of water by the suctioncreated by the passage of such water through an ejector. i

Having described my invention, I claim:

1. 'I'he method of forming foam which comprises feeding into a flowing stream an ingredient adapted to combine with others in said stream to form foam, supplying liquid to said ingredient under atmospheric conditions ybefore the `introduction thereof into said stream, and varying the rate of feed of said ingredient yinto said stream by varying'the amount ,of liquid previously supplied thereto.

2.,'1118 method of forming foam which com- 150? Water mixed with the respective chemicals before` the introduction thereof into such stream.

4. The method of controlling the relative amounts of foam-forming chemicals introduced into a flowing stream which consists in varying the amounts of Water mixed with the respective chemicals before the introduction thereof into such stream.

5. Apparatus for extinguishing res comprising a conduit containing a Venturi tube having a constricted throat, a hopper communicating with said throat, a partition dividing said hopper into separate chambers, by-pass mechanism connecting said conduit with the respective chambers, and valve mechanism controlling the flow to said chambers and decreasing the ilow to one thereof simultaneously with the increase in the flow to the other thereof.

6. Apparatus for extinguishing res comprising a conduit' containing divergent passages, one of said passages containing a screen intercepting the other of said passages, a gage communicating with said last named passage, an ejector communicating with said last named passage, a hopper communicating with said ejector, and means for supplying water from said conduit to said hopper independently of said ejector.

GEORGE GORDON URQUHART. 

